A related art label medium is in a form of a strip, and has a release sheet and an adhesive sheet temporarily adhered to the release sheet. A plurality of label parts is printed on the label medium. In the example shown in FIG. 33, a label medium 201 has rectangular label parts 202 arranged such that three label parts are aligned in a vertical direction and four label parts are aligned in a horizontal direction, and the label medium is half-cut along an outline 203 of each label part 202. Each label part 202 is configured such that the label part 202 can be peeled off from the release sheet by cutting a base layer on which the label part 202 is printed and an adhesive layer provided on the base layer with a plotter cutter or the like and not cutting the release sheet. When using the label medium, a frame part 204 provided outside the label parts 202 is first peeled off from the release sheet, so that only the label parts 202 remain on the release sheet. Accordingly, a user can easily peel off the label parts 202, easily check the remaining number of the label parts 202, and easily manage the number of workers. After that, each label part 202 is sequentially peeled off from the release sheet by the user and is then adhered to a target.
When peeling off the frame part 204 forming a part of the adhesive sheet from the release sheet, in most cases, the user starts to obliquely peel off the frame part 204 from a corner part of the label medium 201, as shown by an arrow 205. When peeling off the frame part 204 from the release sheet, the label part 202 may be peeled off together with the frame part 204 due to the label part 202 being coupled to the frame part 204.
The reason is as follows. Even after the half-cutting, that is, cutting the base layer and the adhesive layer while remaining the release sheet uncut, the cut adhesive layers are again closely contacted to each other. Also, the adhesive layer is sometimes not completely cut. Further, a corner portion 202c of the label part 202 has a small adhesion area between the adhesive sheet and the release sheet. Therefore, a holding force of the adhesive layer of the corner portion to the release sheet is small, so that the label part 202 forming a part of the adhesive sheet and the release sheet are likely to separate from each other. In addition to this, even though the adhesive sheet and the release layer are likely to separate from each other, a peeling force is applied to the corner portion 202c from sides 202a, 202b interposing the corner portion 202c therebetween and the force is thus concentrated thereto.
For this reason, as shown with the arrow 205, when the user starts to peel off the frame part 204 from the release sheet from an oblique direction with respect to a longitudinal direction of the label part 202, if the adhesive layer of the label part 202 and the adhesive layer of the frame part 204 are not sufficiently separated, the label part 202 is coupled to the frame part 204 by the adhesive force of the corresponding part, so that it is peeled off together with the frame part 204.
In such a case, the user has to separate the label part 202 and the frame part 204 while peeling off the frame part 204 from the release sheet, which deteriorates the operation efficiency. Also, the adhesive layer of the label part 202 and the adhesive layer of the frame part 204 may adhere to each other, so that the label medium 201 cannot be used and may be wasted. Further, peeling off the frame part 204 without peeling off the label part 202 together requires skill. Also, separating the coupled label part 202 from the frame part 204 that has already started to be peeled off requires skill.
To address the problem described above, a related art apparatus uses a thermosensitive adhesive tape during the process of thermal transfer printing to peel off the frame part from the release sheet (see, e.g., JP3572840B2). According to another related art apparatus, the frame part is divided into a plurality of sections during the cutting process so that the frame part is easily removed from the release sheet (see, e.g., JP3520693B2).